The story of success isn’t a singular narrative. It’s a series of decisions, of opportunities seized, created, or demanded. The heroes of success stories are never passive.

This is especially true for women in the business world, who make their careers in male-dominated board rooms and executive suites and feel steady pressure to just back-off. Those who succeed push ahead, or, in the words of Facebook chief operating officer Sheryl Sandberg, “lean in.”

Sandberg was in Boston last week speaking to women executives and venture capitalists as she promoted her best-selling book, “Lean In: Women, Work, and the Will to Lead.” The Globe asked women business leaders to recount the decisions that defined their careers — the moments when they leaned in.

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Fay Donohue, president and CEO of Delta Dental of Massachusetts

The world was a different place when Fay Donohue entered the workforce in 1974. Classifieds still read, “Help Wanted, Men” and “Help Wanted, Women.”

Early in her career, Donohue heard she was about to be overlooked for a promotion she desperately wanted. She didn’t understand. She had more experience than her peers and a good reputation in the company.

So Donohue walked into her boss’s office and demanded to know why she wasn’t being considered. “It never crossed his mind that I wanted that promotion because, at the time, I was pregnant,” Donohue, now 62, recalled.

Donohue assured him that she wanted the job. Three months later, she was promoted to become the company’s first female regional director. At the time, she was eight months pregnant.

“You have to speak up,” Donohue said. “Don’t assume that anyone knows anything. If you don’t say you want it, they don’t know you want it.”

Donohue remembered this lesson, when, several years ago, she joined the board of a nonprofit. A few months later, the chairperson left and the board began looking for a new one. At first, Donohue said, she didn’t feel confident enough to put her name in the running.

“Then I realized, I might not know everything but I know I can do this,” Donohue said. “You have to be willing to take risks. Don’t put any blinders on your own head that wouldn’t allow you to move forward.”

She gave the same advice to her three daughters, now grown.

“You have to say yes,” Donohue said. “Whether it’s saying yes to an opportunity or saying yes to finally going to sleep, or saying yes to joining a book club. Say yes to what you need.”

Susan Windham-Bannister, chief executive of the Massachusetts Life Sciences Center

It was 1968, a time of nationwide civil unrest, when a 17-year-old African-American girl from St. Louis looked east. Susan Windham-Bannister applied and was accepted to Wellesley College — becoming one of only 32 black women — just one of eight in her class — at the prestigious women’s college.

As her parents said goodbye, Windham-Bannister recalled, she was scared about Boston’s bitter racial divisions of that era and nervous about entering the elite East Coast school. But she took the leap. Now she sees this decision as one of her most pivotal “leaning in” moments.

“I was the president of my class my freshman year,” she said. “I learned I could come into new situations. If I was just brave, I could not only survive but I could thrive.”

This first leap, and her success at Wellesley, gave her confidence to continue to take chances. After graduating, she decided to stay in Boston, a city not seen as hospitable by many black professionals at the time, and earned her PhD at Brandeis University in Waltham.

Windham-Bannister also remembers moments when she didn’t lean in. She once turned down a promotion at a consulting firm, worried she wasn’t qualified. Later she regretted the decision, believing her self-doubt not only hurt her professionally, but the company as well, as the division she would have led floundered under different leadership.

Key people left, profits declined, and staff was unhappy. “I didn’t demonstrate the courage to step forward and say I’m ready to do this now,’’ she said

Now, at age 61, she runs the state’s quasi-public Massachusetts Life Sciences Center, an agency charged with investing $1 billion in research and economic development in a field largely dominated by men.

Even to this day, she sometimes needs to remind herself to stay confident and strong willed in the face of challenges. Indeed, Sandberg’s book gives her new words to boost her resolve.

“You lean in, more often than not you can be successful at what you are doing,” she said.

Thirty years ago, Helene Solomon was a fresh Boston transplant, her voice still thick with a New York City accent. She was living in Allston/Brighton and working in Mayor Kevin White’s administration.

Boston was just making the change to electing most of the City Council from districts, instead of citywide. All of a sudden, Solomon’s neighbors were knocking on her door, asking for her vote in the district election.

“I thought, I’m just as good and smart and passionate as these guys,” Solomon, now 60, recalled. “Why don’t I run for office?”

She did, becoming the only woman candidate in an eight-person field. Her goal, Solomon said, was to eke out a second-place finish in the primaries, then move on to the general election.

“We didn’t want to come in first and upset all the guys,” she said.

Her plan didn’t work. She won the primary, but narrowly lost the general election.

Still, Solomon said, her campaign was “the seminal experience” of her career. “It provided me with the fire and the fuel that enabled me to have the business I have today,” Solomon said.

Solomon’s decision to run 30 years ago was purely instinctual, she said, and it taught her to trust her gut. She learned to listen to people, she said, a skill that is invaluable in her PR business today.

It also gave her the confidence to take risks. This year, as her company celebrates its 10th anniversary, Solomon is opening a new branch of Solomon McCown in New York — the company’s first expansion outside Boston.

Solomon said this decision was instinctual, much like her decision to run for office years ago.

Her campaign poster still hangs in her downtown Boston office with harbor views.